Understanding the Concepts

* Frequency: The number of waves that pass a point in one second. Measured in Hertz (Hz).

* Time: The duration over which the waves are counted.

Calculations

1. Convert time to seconds: 3 minutes * 60 seconds/minute = 180 seconds

2. Calculate the number of waves: 0.25 Hz * 180 seconds = 45 waves

Answer: 45 waves are made in 3 minutes.